The present invention relates to a hole masking apparatus for masking a through hole perforated in a base plate or material by applying or pasting a seal on the through hole.
During the process of manufacturing a printed wiring board, the step of plugging through holes perforated in a base material of the printed wiring board with a conductive filling material is generally performed by a step of first filling the through holes over the whole surface of the base material by a silk screen method. In this case, before the step of filling with the conductive material over the whole surface of the base material, a masking work is required, by which the open portions of all of the through holes which do not require filling, such as, for example, component attaching holes and the like, are masked.
FIG. 7 shows such a masking work. A base plate or material 10 comprises a plurality of through holes 11 and 12. The through hole 11, for example, is a through hole which is not to be plugged or filled with the conducting material, and the through hole 12 is a through hole which does not need to be plugged or filled. In this case, masking is performed by pasting a seal 13 on the opening portion of the through hole 12.
The reference numeral 14 designates dummy through holes perforated in the base material 10 at opposing positions at the outer periphery side for obtaining a reference position of the base material during various steps of the process of manufacturing a printed wiring board. As shown in FIG. 8, the masking for the through hole 12 which does not require plugging is performed by pasting a seal 13 on both of the opening end portions of the through hole 12. In a conventional process, this pasting of the seal 13 is performed by manual workings.
In FIG. 8, the reference numeral 15 designates a conductive layer formed on one surface of the base material 10.
The conventional masking operation, however, can not eliminate or reduce labor costs because of its manual workings in the conveying of the base material, and it is often necessary to complicate workings further, such as by having to mark the through holes which require masking, and manually cutting and pasting the seal, resulting in a less workable process. Particularly, the masking operation requires pasting a seal onto both surfaces of the base material for a particular through hole, and the aforementioned operations must be repeated so that the efficiency is reduced and production times increase.